Building Codes and Inspections/water heater vent


I installed a fifty gallon natural gas water heater in the attic recently. vented the heater directly out the roof. my question is how far shall the vent be from the chimney siding. it is a combustable material also what is the normal operating temperature of the vent when the water is heating?


You caught me away from home, just returned last night.

You know, there's a possibility of burning your home down here. You really should bring in a licensed plumbing contractor to help you out. Depending on your Authority's regulations, you may be able to apply as a homeowner for a permit and get an inspection to assure your home's and family's safety. I'm sure you saved some money installing it yourself, but you do get what you pay for in this life.

I'm assuming a listed gravity vented water heater with draft hood, let me know if it's another type.

First, the termination of the vent: The vent must terminate two feet above any portion of the building (to include the chimney) within ten feet of the termination; 2012 IFGC para. 503.6.4.2.

Next, clearance to combustibles: 6" required; IFGC Table 503.10.5.

I rarely see water heaters in attics here (Can't think of a single one) due to our cold weather and the associated risk of freezing . You didn't mention the part of the country in which you live. There may be a risk of freezing water piping in the attic there. Then there's the risk of condensation forming within the vent.

Don't forget the required drain pan, overflow, relief, etc.

Can't help you with the temperature of the combustion products. You might check with a thermometer.


Added 2142 hours 03/05/14: Patrick, you're worrying me - 36+ hours and you haven't yet read the reply I spent a good bit of time on; hopefully you'll do that soon.

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Fred Weldin


All aspects of International Mechanical Code, International Energy Conservation Code and International Fuel Gas Code.


I now troubleshoot existing H&AC installations and design H&AC systems and oversee their installations. I have 23 years experience as a H&AC contractor, and I've worked with the tools as a plumber-pipefitter. I'm certified by ICC as a Commercial Mechanical Inspector.


B of ME, numerous factory schools (York, Honeywell, etc.) and Code seminars.

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